For several years the food packaging industry has utilized a packaging film from which bags and casings have been made which are of improved structural soundness such that they have been fully characterized as cook-in. A precooked food product has been attractively packaged using a film within which the product was precooked. The film has been used primarily for cook-and-ship end-use, wherein a meat product is packaged in the film and cooked while in the film, and is thereafter cooled and shipped to wholesaler, retailer, or consumer, without being overwrapped and without having the film stripped therefrom and thereafter being re-packaged in another film.
The phrase “cook-in” as used herein refers to the process of cooking a product packaged in a material capable of withstanding exposure to long and slow cooking conditions while containing the food product, for example cooking at 57° C. to 121° C. (i.e., 135° F.–250° F.) for 2–12 hours, preferably 57° C. to 95° C. (i.e., 135° F.–203° F.) for 2–12 hours. Cook-in packaged foods are essentially pre-packaged, pre-cooked foods which may be directly transferred to the consumer in this form. These types of foods may be consumed with or without warming. Cook-in packaging materials maintain seal integrity, i.e., any heat seals should maintain their integrity during cook-in, and are conformable to the contained food product. Preferably, conformability is achieved by the film being heat-shrinkable so as to form a tightly fitting package. Additional optional characteristics of films for use in cook-in applications include delamination-resistance, low O2-permeability, heat-shrinkability, and optical clarity.
Cook-in films preferably have a tendency for adhesion to the food product, thereby preventing “cook-out”, i.e., “purge”, which is the collection of juices between the outer surface of the food product and the meat-contact surface of the film, i.e., the surface in direct contact with the meat. This meat adhesion characteristic of the meat contact layer serves to both prevent cook-out (and thereby prevent an unattractive package or the need to strip the film from the meat and repackage the meat), to increase product yield, and to prevent the meat from losing juices which improve its edible character. As used herein, the term “adhere”, with respect to meat-adhesion, refers to a meat-contact surface of the film which bonds during cook-in to the contained food product to an extent sufficient to substantially prevent accumulation of fluids between the film and the contained meat product.
It has been found that bone-in meat products, such as ribs, are especially abusive to the cook-in bags in which they are packaged, in spite of the fact that the cook-in film contains polymers such as polyamide, polypropylene, and/or polyester, each of which is more abuse-resistant than, for example, polyolefins. During cooking, shipping, and handling of the packaged meat products, the sharp bone ends tend to cut through the bag, which is undesirable. It would be desirable to provide the cook-in bag with additional resistance to puncture from sharp bone ends.